RESORPTION OF PERITUMOURAL EDEMA IN CEREBRAL GLIOMAS DURING DEXAMETHASONE TREATMENT EVALUATED BY NMR RELAXATION-TIME IMAGING

Peritumoural brain oedema is a prominent feature of malignant brain tu mours. Glucocorticoids diminish the neurological symptoms and signs ca used by the oedema and reduce the abnormally high cerebral water conte nt. The exact mechanisms of action of the glucocorticoids are unknown. The present study investigates the influence of dexamethasone on NMR relaxation time T1 in peritumoural oedema in 13 patients with gliomas. It is shown that NMR T1 images can be used as a potent monitor of bra in oedema, and that dexamethasone significantly reduces mean T1 after 1, 3, and 7 days of treatment by 2%, 6%, and 13% respectively. Using a n image histogram analysis technique the term ''superoedema'' was defi ned as the 50% of the total oedema area with the highest T1, correspon ding to the highest water content. It is shown, that with this techniq ue the treatment effect of steroids on superoedema was a reduction of 13%, 33%, and 57% after 1, 3, and 7 days of treatment respectively. Th e mean change after 24 hours of treatment was statistically significan t (p < 0.01). The method can be used in all situations where the anti- oedematous effect of a given treatment is to be monitored.